Madagascar Hissing Cockroaches (Grompadorhina portentosa) are extremely popular as pets, classroom animals and reptile food. Recent studies at Ohio State University have revealed a darker side to these otherwise harmless insects…their bodies and wastes are colonized by 14 mold species, several of which can cause allergic reactions and secondary infections. I’ve worked with huge colonies of these and other feeder insects in zoos, and coworkers seem to have developed allergies to crickets, but I have not heard of similar reports concerning roaches. As of now, precautions rather than outright avoidance of Hissing Roaches are being advised.

Allergic Reactions and Secondary Infections

The study, published in the March, 2014 issue of the journal Mycoses (V. 57, N. 3), examined Hissing Roach colonies in schools, zoos, homes, and pet stores. Molds of various species were found on shed skins, feces and the bodies of live insects. Several of the molds are capable of triggering allergic reactions such as skin and eye irritation, wheezing and nasal congestion; sensitive individuals could be at additional risk. Aspergillus niger, which is commonly associated with contaminated foods, was especially numerous (see photo). People are impacted mainly via mold spores that land on the skin or are inhaled.

Uploaded to Wikipedia Commons by S. K. Mohan

Several of the molds found on Hissing Roaches can also cause secondary infections in wounds or the lungs.

At present, researchers advise those working with Hissing Roaches to wash their hands after contact with the insects. I would suggest that, as with all pets, a doctor should be consulted if you have concerns, or suspect that you or a household member may be at risk.

Hissing Cockroach Care Tips

Molds are fungi that thrive in moist environments. In order to help lower your roach enclosure’s humidity level, I recommend that cricket gel cubes be used as a water source; please see this article for further information. Gel tubes eliminate the need for damp sponges and water bowls, and also prevent nymphs from drowning. Fruit, which is also an important source of water and nutrients, should be replaced regularly to prevent spoilage and mold.

Regular cleaning of the terrarium and replacement of cardboard sheltering sites (if used) is important; Zoo Med’s Wipeout Terrarium Cleaner or a solution of 1 oz. of bleach per gallon of water can be empoloyed. I keep Madagascar Hissing Roach colonies in bare-bottomed tanks; substrate is not necessary, and it complicates cleaning. This type of housing also enables one to maintain a dry environment, which should, in theory, assist in mold control (I’ve not checked into exactly how much moisture the roach-associated molds require…any insights appreciated).

Uploaded to Wikipedia Commons by Sarefo

Mites to the Rescue

Researchers are now studying a type of mite (Gromphadorholaelaps schafeiri, see photo) that commonly lives on and around Hissing Roaches. By consuming organic debris, these mites may help to limit mold growth. Many scorpion, millipede and tarantula owners are familiar with other tiny white mites that often establish themselves in invertebrate terrariums. Although disconcerting when first seen, most are harmless or perhaps even useful…please see the article linked below for information about their habits and tips on mite control.

Other Roaches

Whether you keep them as pets or a reptile food-source, roaches are a most fascinating group of insects. Their fossil record stretches back over 300 million years, and 4,000+ species have been described to date. Latin America’s Megaloblatta baberoides sports a 7 inch wingspan while the heaviest, Macropameothia rhinoceros of Australia, weighs in at 1 ½ ounces. Among the most interesting new discoveries is an African cockroach that resembles and behaves like a grasshopper.

The Orange-Spotted Guyana Roach (Blaptica dubia) has much to recommend it as both a food animal and terrarium subject. Please see the article linked below to read more about its natural history and care.

2 comments

Great bit of information, but seems to focus on hisser roaches (or target them), when they in fact have these symbiotic mites that keep the food sources for fungal infections down. I would love to hear how often these fungus spp described are found living on surrounding plant containers and other roach species to put it into perspective.

Also, something they really should be studying, is how the roaches manage to survive if in fact a deadly strain like Aspergillus niger is living on/around them.

About Frank Indiviglio

Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.

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